The Psuhoffman Storm

[Ellinwood]

Do the snow maps take such low ratios into account?

Perhaps this is where we can get some dtk insight... the GFS puts out an actual snowfall variable, but I am unsure in how it is calculated.

[psuhoffman]

Do the snow maps take such low ratios into account?

Don't use those maps, there is a reason they are called clown maps

[weathercoins]

Another consideration with this wet snow is the ratios. 10-1 would be a pipedream, even 8-1 too high. What you would likely see is heavy, wet large conglomerated flakes that melt early on then accumulate and compact into a wet, moisture laden snow. 6-1 would probably be a realistic snow ratio. 5-7" would be a high end threat even with the crazy NAM, 2-4/3-5" is a realistic threat as is verbatim.

Very true. For those of us wondering about missing school/work (I have a serious case of jet lag I can't overcome with my schedule, and UMD started today...), wet snow is wonderful though for closing things .

[baroclinic_instability]

Do the snow maps take such low ratios into account?

Typical clown maps do not. I can't speak for the map Ellinwood posted from MDA, but most companies like that have an "automated" snow map that is typically altered by the forecaster. The one posted by Ellinwood may have been altered by the forecaster--not sure. I can say for sure the twisterdata snow maps should be taken with a grain of salt. 8-12" from SV has to be 10-1 type ratios to spit out those snow values.

[Ian]

Another consideration with this wet snow is the ratios. 10-1 would be a pipedream, even 8-1 too high. What you would likely see is heavy, wet large conglomerated flakes that melt early on then accumulate and compact into a wet, moisture laden snow. 6-1 would probably be a realistic snow ratio. 5-7" would be a high end threat even with the crazy NAM, 2-4/3-5" is a realistic threat as is verbatim.

im not sure i'd bank on super low ratio snow from the ull especially if there is any convective banding and such. i mean as you transition it's going to be slop but if you get into sustained rates you'll do better.

[RTutton]

Another consideration with this wet snow is the ratios. 10-1 would be a pipedream, even 8-1 too high. What you would likely see is heavy, wet large conglomerated flakes that melt early on then accumulate and compact into a wet, moisture laden snow. 6-1 would probably be a realistic snow ratio. 5-7" would be a high end threat even with the crazy NAM, 2-4/3-5" is a realistic threat as is verbatim.

One of the best points I've seen in here all day, despite my excitement and hope for accumulating snow.

[Ellinwood]

Typical clown maps do not. I can't speak for the map Ellinwood posted from MDA, but most companies like that have an "automated" snow map that is typically altered by the forecaster. The one posted by Ellinwood may have been altered by the forecaster--not sure. I can say for sure the twisterdata snow maps should be taken with a grain of salt. 8-12" from SV has to be 10-1 type ratios to spit out those snow values.

It's pure GFS.

[psuhoffman]

Perhaps this is where we can get some dtk insight... the GFS puts out an actual snowfall variable, but I am unsure in how it is calculated.

[baroclinic_instability]

im not sure i'd bank on super low ratio snow from the ull especially if there is any convective banding and such. i mean as you transition it's going to be slop but if you get into sustained rates you'll do better.

The main reason I am going with the low ratios is the sounding being nearly isothermal up to 10,000 feet. -2 to -3 is a snow crystal growth no mans land. Convective forcing would need to extend past 10, 000 feet--hence why I would rather have the NAM and its solution with an upper low closer. GFS is too far SE with the upper low and the lapse rates would not be as conducive to convective forcing and therefore the good snow crystal growth region.

[Ian]

The main reason I am going with the low ratios is the sounding being nearly isothermal up to 10,000 feet. -2 to -3 is a snow crystal growth no mans land. Convective forcing would need to extend past 10, 000 feet--hence why I would rather have the NAM and its solution with an upper low closer. GFS is too far SE with the upper low and the lapse rates would not be as conducive to convective forcing and therefore the good snow crystal growth region.

i was sort of blending the outputs in my head. i have not looked and many soundings other than what's posted here. in my head 6:1 would be a stretch!

[baroclinic_instability]

One of the best points I've seen in here all day, despite my excitement and hope for accumulating snow.

The threat for accumulating snow is becoming very high--I think all folks should be excited for that alone. The fact we are discussing snow ratios is a good start.

[Bob Chill]

The threat for accumulating snow is becoming very high--I think all folks should be excited for that alone. The fact we are discussing snow ratios is a good start.

Thank you for this. Until today, the only ratio we discussed was liquid vs frozen.Accumulating snow is more than we can ask for given our track record this year.

[NinjaWarrior2]

Looking on GFS soundings, It keeps dew points below freezing for BWI

[baroclinic_instability]

i was sort of blending the outputs in my head. i have not looked and many soundings other than what's posted here. in my head 6:1 would be a stretch!

You would be surprised what an isothermal sounding like that can produce. SNow ratios of 6-1 are not rare. This is such a compact PV max steep lapse rates above 600 hpa overlaying the low level region below freezing are going to be hard to come by. A pretty small region we are talking. Ellinwoods snow map (that he made) from a couple days ago with the thin region is realistic.

[SeanVA]

<6:1 sounds rediculously marginal

[cajuncook]

When it snows hard enough, it is only a matter of time before it starts sticking. There's no way we get .5"+ of QPF as snow, in a few hours, and have no accumulation.

No, I agree. Just not seeing a Feb 2010 storm, although the maximum potential of this storm is around there.

[Huffwx]

Local met makes his call for my region..

Note the "Huffman Solution"

[baroclinic_instability]

The ratios become better halfway through the changeover as the mid level heights continue to fall and the soundings cools. By then the ending of precip will be occurring though.

[Bob Chill]

Local met makes his call for my region..

Note the "Huffman Solution"

Are you trying to steal the Hoffman solution? He is the founder of this.

jk of course. I would be excited if I were you. Good chance at some pretty ridiculous rates down there. Going to be a blast to watch if everything comes together as modeled.

[SomeguyfromTakomaPark]

No, I agree. Just not seeing a Feb 2010 storm, although the maximum potential of this storm is around there.

How is this potential of this storm near either of the Feb 2010 storms?

EDIT: I see which one you are talking about now, my bad.

[Huffwx]

Are you trying to steal the Hoffman solution? He is the founder of this.

jk of course. I would be excited if I were you. Good chance at some pretty ridiculous rates down there. Going to be a blast to watch if everything comes together as modeled.

I'd trust the EC on the track of the 500 mb low over the GFS--- and that matches the NAM 18z which rocks.

[Dcwx]

Note that I was referring to February 2, which brought 3-5" of wet snow to the area.

That was a really nice storm. Had dinner with family and friends for my birthday. Went into the restaurant with just a dusting on the ground, came out to several inches and tough road conditions. I am actually fond of wet snow, I think its pretty despite marginal accumulations.

If this event can produce the same way, I will certainly be happy.

[CarolineWx]

[samdman95]

While yes, these 18z runs look great and the trend looks nice, let's not forget that yesterdays 18z runs were both total crap OTS. Yes, I'm starting to get excited but let's wait until the 0z suite to get uber-pumped.

[Inudaw]

Still think RIC is going to be mostly rain. I don't think the band of snow that will develop with the upper low will be as far south as RIC is. Could see some snow showers at the end maybe. ><;

[real]

Feb/ 2 was am awful storm if you lived in DC, but noone really cared cause the Big Dog was already being majorly hyped as being right around the corner.

Forecasts were for 3 to 6 inches and WSW were up, but the gradient across the city was among the steepest I have ever seen.

From about Columbia Heights-Adams Morgan south to the Potomac River there was maybe a half-inch accumulation on the grass and nothing on the pavement from that storm, despite constant snowfall from like 5 p.m. to midnight.

But I remember driving home that evening late and by the time you got to Upper Northwest there was a plowable 5 inches on everything.

Just something to think about for this storm if someone has to make a forecast and using that as a possible comparision. May want to make a special exclusion zone for much of the city if things look similar to that storm regards to temps, which seems like a strong possibility.

[Dalfy]

Another consideration with this wet snow is the ratios. 10-1 would be a pipedream, even 8-1 too high. What you would likely see is heavy, wet large conglomerated flakes that melt early on then accumulate and compact into a wet, moisture laden snow. 6-1 would probably be a realistic snow ratio. 5-7" would be a high end threat even with the crazy NAM, 2-4/3-5" is a realistic threat as is verbatim.

Why would the ratios be so low? The thickness at 1000-500mb is just below 540 with the warm layer between 700-850, wouldnt that just be 10-1 ratios?

Edit: nevermind, just saw your other post on it..

[Dr No]

Feb/ 2 was am awful storm if you lived in DC, but noone really cared cause the Big Dog was already being majorly hyped as being right around the corner.

Forecasts were for 3 to 6 inches and WSW were up, but the gradient across the city was among the steepest I have ever seen.

From about Columbia Heights-Adams Morgan south to the Potomac River there was maybe a half-inch accumulation on the grass and nothing on the pavement from that storm, despite constant snowfall from like 5 p.m. to midnight.

But I remember driving home that evening late and by the time you got to Upper Northwest there was a plowable 5 inches on everything.

Just something to think about for this storm if someone has to make a forecast and using that as a possible comparision. May want to make a special exclusion zone for much of the city if things look similar to that storm regards to temps, which seems like a strong possibility.

Great storm out west 5.8" IMBY. Alot more QPF forecasted for this upcoming one.

[SomeguyfromTakomaPark]

Feb/ 2 was am awful storm if you lived in DC, but noone really cared cause the Big Dog was already being majorly hyped as being right around the corner.

Forecasts were for 3 to 6 inches and WSW were up, but the gradient across the city was among the steepest I have ever seen.

From about Columbia Heights-Adams Morgan south to the Potomac River there was maybe a half-inch accumulation on the grass and nothing on the pavement from that storm, despite constant snowfall from like 5 p.m. to midnight.

But I remember driving home that evening late and by the time you got to Upper Northwest there was a plowable 5 inches on everything.

Just something to think about for this storm if someone has to make a forecast and using that as a possible comparision. May want to make a special exclusion zone for much of the city if things look similar to that storm regards to temps, which seems like a strong possibility.

I remember there being at least 2-3 inches on the grass here around 13th and Harvard.

[Bob Chill]

Great storm out west 5.8" IMBY. Alot more QPF forecasted for this upcoming one.

Speaking of QPF with this storm, I think we'll see 0z back off on that and it might be a good thing. The front end will do nothing for us except rain. We've seen models trend away from front end QPF and give us mostly ULL precip on the back. This is a good trend if we want acc snow around here.